This invention relates to circuit breaker control circuitry, and more particularly to control circuitry that controls the operation of a circuit breaker in such a manner that the circuit breaker contacts always open at a zero load current crossing.
When circuit breaker contacts connecting a load to a power source are opened, an arc is developed across the contacts as the contacts separate. This arcing, no matter how small, has a deleterious effect on the circuit breaker contacts and can become dangerous or hazardous when large currents are involved since the magnitude of the arcing is directly related to the magnitude of the current flowing through the contacts when the contacts are opened.
Since the magnitude of the arcing is directly related to the magnitude of the current flowing through the contacts when the contacts are opened, it is obvious that this arcing can be eliminated if the contacts are opened at a zero load current crossing point. This invention provides control circuitry that assures that the contacts of a circuit breaker always open at a zero load current crossing point. If the contacts of a circuit breaker are opened precisely at a zero load current crossing, no arcing will take place and therefore the contacts of the circuit breaker will not be subjected to the usual deleterious burning and pitting caused by arcing.